Anionic polymerization techniques have been used to synthesize polymers that are useful in the manufacture of tires. Certain initiators impart a functional group to the polymer, and these functional groups are believed to have a beneficial impact on the performance of tires.
The synthesis of polymers by anionic polymerization is often advantageously conducted in non-polar organic solvent. It is therefore desirable that the initiator compounds bearing the functional groups exhibit some useful degree of solubility in these solvents. In particular, it is highly desirable to employ aliphatic solvents such as technical hexanes, and therefore initiator compounds that exhibit useful solubility in these solvents are likewise highly advantageous.
Unfortunately, inasmuch functional initiators often include metallated organic ligands that include one or more hetero atoms, the solubility of these compounds in solvents, particularly aliphatic solvents, is limited. Moreover, the ability to predict which compounds are soluble in aliphatic solvents is extremely difficult inasmuch as the metallation of the organic species often alters the solubility characteristics.
Because functional initiators remain desirable, particularly for the synthesis for functionalized polymers that are used in the manufacture of tires, there is a continued desire to identify initiators that can lead to technologically useful polymers and that exhibit a technologically useful solubility in aliphatic solvents in order to facilitate the polymerization process.